This project is concerned with the retention and immediate processing of visual information. The principal questions it addresses are: What is the nature of the representations in long-term memory for categories of visual stimuli? How do such representations differ from those of specific visual stimuli; from semantic information in general? How are these representations utilized when visual stimuli are presented? What information is provided by a physically present visual event that is provided differently or is absent in its long-term-memory counterpart? The project adddresses such questions by asking subjects to perform tasks with visual stimuli and measuring their speed and/or accuracy. A variety of tasks are used, including making semantic judgments about pictures (e.g., is it a living thing?), mentally synthesizing whole forms from fragments, judging relative distances between points on a map, studying a set of forms for later retention, or judging the applicability of a label with respect to a visual stimulus. The tasks serve two different functions: They manipulate immediate processing of information in memory; for example, how a form is encoded. And, they assess what information is retained and how effectively.